Poly(arylene sulfide ketone)s, PASK, are useful engineering thermoplastics for film, fiber, molding, and composite applications because of their high melting points. One process for producing poly(arylene sulfide ketone)s involves the reaction of a polyhalobenzophenone such as dichlorobenzophenone with an alkali metal sulfide in a polar organic solvent. The alkali metal sulfide can be added as such or can be prepared from the reaction of an alkali metal hydrosulfide with an alkali metal hydroxide using an equal molar amount of the alkali metal hydrosulfide with respect to the alkali metal hydroxide. However, a major disadvantage is that the poly(arylene sulfide ketone)s so produced are of low molecular weight and low melt stability.
Poly(arylene sulfide ketone)s of high molecular weight are desirable because they possess good mechanical properties. If an excess amount of alkali metal hydrosulfide is present during the polymerization reaction, poly(arylene sulfide ketone)s of high molecular weight can be produced. This means that a molar excess of alkali metal hydrosulfide with respect to the alkali metal hydroxide is present when the alkali metal sulfide is prepared, or that some alkali metal hydrosulfide is added with the alkali metal sulfide.
In addition to high molecular weight, processability is another desirable property that poly(arylene sulfide ketone)s should possess. Processability means that a polymer is able to be processed by conventional means and, therefore, can be commercially useful. The processability of a polymer depends upon the polymer's melt stability. This means that if a polymer is melt stable it will generally also be processable. Poly(arylene sulfide ketone)s produced by prior methods are not very melt stable and, therefore, are not processable. Even high molecular weight poly(arylene sulfide ketone)s produced with excess alkali metal hydrosulfide are not very melt stable.
It would be most desirable to be able to produce melt stable poly(arylene sulfide ketone)s having a high molecular weight
It is an object of our invention to provide a process for preparing high molecular weight poly(arylene sulfide ketone)s. It is a further object of our invention to provide a process for preparing melt stable poly(arylene sulfide ketone)s. It is a further object of our invention to prepare novel melt stable poly(arylene sulfide ketone)s. It is yet a further object of our invention to prepare novel melt stable, high molecular weight poly(arylene sulfide ketone)s.